Predictions of strengths of long-term variations in sunspot activity

Abstract

Recently, using Greenwich data (1879-1976) and SOON/NOAA data (1977-2002) on sunspot groups we found a big or a moderate drop in the solar equatorial rotation rate, A, occurred after every four solar cycles suggesting the existence of ``double Hale cycle (DHC)" and ``Gleissberg cycle (GC)" in A. We also found the existence of ``Hale cycle (HC)" and GC in the latitude gradient of the rotation, B (Javaraiah \cite{Javaraiah}). Using these results here we made forecasts for the following: (i) epochs of the forthcoming big and moderate drops in A; (ii) the epoch of maximum |B| during the current GC of B; (iii) the strengths of DHCs and HCs of sunspot activity which follow the big and the moderate drops in A; (iv) violation of the Gnevyshev & Ohl rule during the current HC 11 which consists of cycles 22 and 23; and (v) deduced the near complete absence of sunspot activity during the deep Maunder minimum.